Example embodiments of inventive concepts relate to a complementary metal oxide semiconductor (CMOS) image sensor.
The CMOS image sensor is a solid-state image sensing device using a complementary metal oxide semiconductor (CMOS). The CMOS image sensor has a lower manufacturing cost than a charge coupled device (CCD) image sensor including a high-voltage analog circuit, and consumes less power due to the small size thereof.
Recently, as the CMOS image sensor has improved in performance, the CMOS image sensor has been used in various consumer electronics in addition to portable electronic devices such as smart phones and digital cameras. The CMOS image sensor includes a photo-electric conversion element configured to receive light and convert the light into an electrical signal. The more light received by the photo-electric conversion element, the better the photo sensitivity of the CMOS image sensor.
As the CMOS image sensor has recently become smaller, that the sensitivity of the CMOS image sensor lowers. For example, as a pixel of an image sensor becomes smaller, a photo-electric conversion element of the pixel decreases in size and the sensitivity of the CMOS image sensor is affected by the size of the pixel.